Table 4.
Bladder Cancer Risk Associated With Different Indices of Lifetime Trihalomethane Exposure, Spanish Bladder Cancer Study, Spain, 1998–2001
| Model | No. of Cases | No. of Controls | Odds Ratioa | 95% Confidence Interval |
|---|---|---|---|---|
| TTHM, µg/L | ||||
| Q1 (<9.4) | 159 | 200 | 1.00 | Reference |
| Q2 (9.4–<27.4) | 166 | 193 | 1.22 | 0.8, 1.88 |
| Q3 (27.4–<49.8) | 194 | 166 | 2.06 | 1.2, 3.55 |
| Q4 (≥49.8) | 167 | 191 | 2.09 | 1.1, 3.98 |
| Ptrend | 0.008 | |||
| Cytotoxicity- weighted TTHM, µg/L | ||||
| Q1 (<5) | 165 | 194 | 1.00 | Reference |
| Q2 (5–<11.4) | 165 | 196 | 1.03 | 0.73, 1.44 |
| Q3 (11.4–<24.8) | 192 | 165 | 1.65 | 0.89, 3.06 |
| Q4 (≥24.8) | 164 | 195 | 1.56 | 0.7, 3.45 |
| Ptrend | 0.083 | |||
| Molar concentration of TTHM, pmol/L | ||||
| Q1 (<0.06) | 162 | 198 | 1.00 | Reference |
| Q2 (0.06–<0.21) | 167 | 191 | 1.17 | 0.73, 1.89 |
| Q3 (0.21–<0.34) | 191 | 168 | 1.74 | 0.92, 3.29 |
| Q4 (≥0.34) | 166 | 193 | 1.52 | 0.67, 3.45 |
| Ptrend | 0.075 | |||
| Chloroform and brominated THM, mutually adjusted | ||||
| Chloroform, µg/L | ||||
| Q1 (<3.4) | 160 | 199 | 1.00 | Reference |
| Q2 (3.4–<15) | 176 | 183 | 1.43 | 0.83, 2.48 |
| Q3 (15–<21.2) | 170 | 189 | 1.34 | 0.65, 2.75 |
| Q4 (≥21.2) | 180 | 179 | 1.76 | 0.91, 3.39 |
| Ptrend | 0.119 | |||
| Brominated THM, µg/L | ||||
| Q1 (<3.8) | 158 | 201 | 1.00 | Reference |
| Q2 (3.8–<6.2) | 180 | 180 | 1.14 | 0.75, 1.75 |
| Q3 (6.2–<29.1) | 181 | 177 | 1.04 | 0.68, 1.57 |
| Q4 (≥29.1) | 167 | 192 | 1.05 | 0.55, 2 |
| Ptrend | 0.773 | |||
| Scores from principal- components analysis, mutually adjusted | ||||
| Chlorinated THM score | ||||
| Q1 (<−1.02) | 160 | 199 | 1.00 | Reference |
| Q2 (−1.02 to <−0.09) | 176 | 183 | 0.77 | 0.53, 1.13 |
| Q3 (−0.09 to <0.78) | 170 | 189 | 0.90 | 0.54, 1.48 |
| Q4 (≥0.78) | 180 | 179 | 0.83 | 0.49, 1.39 |
| Ptrend | 0.835 | |||
| Brominated THM score | ||||
| Q1 (<−1.20) | 168 | 191 | 1.00 | Reference |
| Q2 (−1.20 to <−0.72) | 167 | 192 | 1.08 | 0.66, 1.79 |
| Q3 (−0.72 to <0.77) | 185 | 177 | 1.67 | 0.71, 3.96 |
| Q4 (≥0.77) | 166 | 190 | 1.74 | 0.69, 4.39 |
| Ptrend | 0.190 | |||
Abbreviations: Q, quartile; THM, trihalomethanes; TTHM, total trihalomethanes.
a Odds ratios from conditional logistic regression models stratified by matched set. Cases and controls were matched on sex, age (in 5-year groups), and geographical area. Odds ratios were adjusted for smoking status (never, ever, or current smoker), ever having worked in a profession with high risk for bladder cancer (yes, no), and quartile of fruit and vegetable consumption (g/day).